Chlamydial heat-shock protein 60 : A marker for chronic infection with Chlamydia Pneumoniae in atherosclerosis: Investigation of atherosclerotic coronary arteries by immunocytochemistry.

Worldwide, ischemic heart disease is an important cause of death and there is an increasing number of pointers toward a causative connection between Chlamydia pneumoniae and atherosclerosis. The presence, localization, and relationship to atheroma of Chlamydial heat-shock protein 60 (cHsp60) in coronary tissue was investigated by immunocytochemical methods and by different investigators. In the present study, for the first time, arterial segments, including the whole course of the great coronary arteries from proximal to distal, were investigated by immunocytochemistry to detect cHsp60. Specimens from coronary arteries of 46 autopsy cases (17 females, 29 males; mean age: 62.7 years, SD 17.9 years) were examined (480 paraffin-embedded samples; 11 sites from each case). Different fixatives were used for the specimens taken at autopsy. Immunocytochemical staining was done using an anti-cHsp60 antibody (Affinity Bioreagents Inc.) and a modified Labeled-Strept-Avidine-Biotin-staining protocol (DAKO). The localization of signals by site of predilection in the course of coronary vessels and by coincidence with specific structural characteristics, was detected by light microscopy. Detection of cHsp60 was possible in 30 of 46 (65.2%) individuals (minimum one sample) and in 87 of 480 specimens (18.1%). The distribution of the signals was correlated to the intensity of atherosclerosis (mild to middle) and a decreasing frequency from proximal to distal arterial segments was found. Macroscopically, nonatherosclerotic vessels presented cHsp60 only occasionally. In accordance with recent publications, cHsp60 was detected in foam cells and macrophages, cell-poor regions, and thickened intimal layers, and more rarely in inflammatory infiltrates and calcified areas. According to previous studies, a distribution independent from atherosclerotic lesions was not found. Detection of cHsp60 was superior using Notox(®) (Earth Industries) as a fixative in comparison with buffered formaldehyde.